Helping a buddy out with his AMC 20.. he wanted to stitch the tubes and do a simple truss... so I used some scraps I had laying around...
While I have his stripped axle, I think I'm gonna make a template of the housing to make this an easier job next time.

I'll be doing this once I get mine running. Q for ya - On the stitch welding on the housing, any special considerations/procedures that have to be taken into account since you are welding mild steel to cast? I know for welding cast there are special wire/rods that must be used, but is this necessary for the stitch welding also?

Second - How do you feel the tube truss like you have here compare to the plate/beam type trusses that have been on here so often? Thanks

I'll be doing this once I get mine running. Q for ya - On the stitch welding on the housing, any special considerations/procedures that have to be taken into account since you are welding mild steel to cast? I know for welding cast there are special wire/rods that must be used, but is this necessary for the stitch welding also?

Second - How do you feel the tube truss like you have here compare to the plate/beam type trusses that have been on here so often? Thanks

I've welded cast to steel before using high nickel rods, 7018 rods, flux core mig (.035") and regular solid core mig with gas.. and haven't really noticed any difference between any of them. I try to lay on a good thick bead to better mix the cast and steel together in the bead itself.. seems to prevent cracking. Also, instead of stopping my bead like I normally do, I finish by staying in one place for about 2 seconds or so to finish off with a nice "blob" of weld. This has resisted cracking better for me. Normally, when welding cast to steel, if it's gonna crack, it does it almost immediately. You can watch the crack propogate as soon as the puddle freezes and starts to cool.. it's pretty cool actually. For stitching I now just use my mig with gas.

I'd prefer to use a beam type truss but that is way labor intensive compared to doing a tube type. This axle is intended for up to medium offroad work with probably no bigger than 33" tires.. no hard core rock crawling, big rubber or hard launches in its future so a tube type truss should be plenty.

In this month's JP mag, they wrote about how the amc 20 is junk and how it's difficult to weld on the tubes because they are so thin they warp very easily. It's another reason why I get annoyed with JP because if the axle isn't a massive dana 60 or rockwell, they crap all over it.

So how's your experience with them Besrk; easy, moderate or difficult.

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Quote:

Originally Posted by jeep-jeep-01
And by the look of his avatar and name... not a hippie.

In this month's JP mag, they wrote about how the amc 20 is junk and how it's difficult to weld on the tubes because they are so thin they warp very easily. It's another reason why I get annoyed with JP because if the axle isn't a massive dana 60 or rockwell, they crap all over it.

So how's your experience with them Besrk; easy, moderate or difficult.

I mig with a 150 amp my tubing with no cracks or wraps. It is did wrap it then it must have un-wrap the wrap that was there.

I just bent a 23" 1 3/4 tubing and welded the sides on. Fixed my problem of the axle tube twisting.

Only people that say amc20 are junk are the ones selling replacements.

Of course I am easy on the trails. I am not there to impress people by slamming the pedal down to the floor. I am try to go not stop and slow.

Basically, it is just added support for the relatively weak (in comparison to say... a Dana 60) axle tubes.

As for JP mag... it is written by guys and gals just like you and me. I learned a long time ago to form my own opinions about things. Almost everything I've learned, I learned from the "school of hard knocks" and mistakes. Rarely do I make the same mistake twice. Honestly, I have stitched up the tubes on probably 7-8 AMC20s without problems. Yeah.. if you tried to run a long continuous bead of weld you can warp it.. you can warp anything if you try to. Key is to weld small areas and move around. If I do a 1" stitch on one side, I flip it over and do the next one on the opposite side. Then, I go to the other axle tube and do the same while the first one cools a bit. It's not difficult to predict how the metal is going to react with the heat distortion and the expansion/contraction associated with the welding heat. With a little experience and some common sense, you can keep distortion to a minimum.

One thing I am striving for on this axle is to keep the truss from "pulling" up on the ends of the axle tubes. If you were to jump a Jeep (trying to bend the axle), it will bend "up" at the axle ends(sort of like a smiley face). Ideally, a truss across the bottom of the axle would be the best way to prevent bending the axle housing as the truss would be loaded in tension upon the tires' impact with the ground. However, who wants a big chunk of steel welded across the bottom of their axle housing to drag around on the ground?.. So, most trusses (we're not talking Baja racers here), are a compromise and welded on the top of the housing. While maybe not as effective, it does still help to increase the axle housing's resistance to bending. However, if care is not taken, the truss itself can actually pull up on the axle tube ends as the welding cools. I made this truss so that it sits on those two ends with about a 1/8" gap under the center (between the housing and the bent tube piece). I'll weld the ends first (a little at a time to prevent warping), then I'll clamp the center down to the cast section and weld it. That will slightly "load" the truss.. pushing down a little on the ends...